OBJECTIVE: To review the incidence of subsequent (metachronous) microscopically confirmed, clinically apparent new primary cancers in more than 28,000 index cancer patients diagnosed during 1965-71 at the Memorial Hospital for Cancer and Allied Diseases. In particular the focus of this study will be on more than 2600 children and adult patients diagnosed with lymphoreticular cancers, solid sarcomas, Wilm's tumor and neuroblastoma and 733 adult patients with epidermoid carcinoma of the oral cavity, pharynx or larynx. APPROACH: With respect to the cohorts of patients diagnosed during 1965-71 with lymphoreticular cancers, solid sarcomas, Wilms' tumor or neuroblastoma, any apparent excess in the risk of multiple primaries will be reviewed in relation to the nature, degree and ordered sequence of prior radiotherapy and chemotherapy. The Cancer Registry will identify patients by broad treatment categories, but individual charts will be reviewed to determine dosage, quality of radiotherapy and specific nature of chemotherapeutic agents and ordered sequence of radiotherapy and chemotherapy. Person-years at risk will be derived within each cancer cohort for appropriate levels of exposure to chemotherapy and/or radiotherapy. The appropriate levels for the analysis of the risk of exposure to chemotherapy and/or radiotherapy will be determined without prior knowledge of the subsequent occurrence of new primary cancers. A major constraint in selecting exposure levels will be the adequacy of the sample size and the accumulating person-years at risk. The observed number of new primary cancers will be compared with that expected. A similar analysis in relation to appropriate levels of exposure to chemotherapy and/or radiotherapy will be made for each corresponding anatomic-morphologic cohort diagnosed during 1949-62 and with follow-up concluded as of December 31, 1962. To derive the expected number of new primary cancers in this instance, the observations summarized for 1949-54 will be multiplied by the appropriate age-sex-site-specific incidence rates in New York State for 1949-51, and those for 1955-62 by the rates for 1958-60.